1. Field of the Invention:
This invention relates to a system for monitoring the movement of a ribbon e.g. a glass ribbon, to actuate ribbon severing equipment and to a system for determining the continuity of the ribbon.
2. Discussion of the Prior Art and Technical Problems:
In the glassmaking industry, continuous glass ribbons are inspected and subsequently cut into usable glass sheets. U.S. Pat. Nos. 3,191,857 and 3,216,809 teach various methods that are used for inspecting glass ribbons for subsequently cutting the glass ribbon into sheets of a predetermined width.
U.S. Pat. Nos. 3,282,140; 3,419,374; 3,539,324; 3,581,615 and 3,802,306 different apparatuses that may be used for monitoring the movement of the ribbon and actuating severing equipment to cut a ribbon into sheets. In general, the patents teach the use of a wheel in contact with the glass ribbon to monitor ribbon displacement. The wheel may be connected to pulse generating equipment to generate pulses as a function of ribbon displacement which pulses are subsequently converted into units of length. One of the drawbacks of using a ribbon-driven wheel for generating pulses is that changes in the wheel diameter as a result of operation variables, e.g., particle pick up, or wheel wear can increase or decrease the wheel diameter which results in randomly increasing or decreasing pulse counts for a given ribbon displacement.
The use of displacement detectors, e.g., roto pulsers, is not limited to the glass industry. For example, U.S. Pat. Nos. 3,215,015; 3,406,601; 3,429,491; 3,556,368; 3,628,450; 3,732,762; and 4,044,639 teach, among other things, the use of ribbon-driven wheels in the steel, paper and plastic industries for measuring ribbon displacement and/or for determining ribbon breaks. The drawbacks of using a ribbon driven wheel was discussed supra regarding their use in measuring glass ribbons.
U.S. Pat. No. 3,949,856 teaches a system for monitoring paper feed in printing mechanisms in which signals from two systems each actuated by wheels driven by a paper ribbon are compared to determine ribbon continuity. The drawback of the system taught in U.S. Pat. No. 3,949,856 is that both signals are generated by the movement of the paper ribbon. For example, one of the signals is generated by the paper frictionally driving a wheel and the other signal is generated by a wheel having gear teeth engaging holes in the edges of the paper ribbon. With the wheel arrangement taught in the U.S. Pat. No. 3,949,856, wheel(s) wear, dirt pickup, or variations in engaging holes at the marginal edge of the ribbon can randomly vary the difference in pulse counts between the wheels which may result in erroneous conclusions.
It would be advantageous, therefore, to provide a system for (1) monitoring the movement of a substrate, e.g., a glass ribbon, to actuate equipment, e.g., glass scoring and snapping equipment and (2) for determining the continuity of the ribbon, that does not have the limitations and/or drawbacks of the prior art.